from decimal import Decimal

from django.contrib.auth import get_user_model
from django.test import TestCase
from django.utils import timezone

from apps.accounts.models import Customer
from apps.core.errors import ApiError
from apps.orders.services import OrderService
from apps.pricing.models import PricingRule
from apps.reservations.models import Facility, Reservation, Slot
from apps.workflows.engine import WorkflowEngine
from apps.workflows.models import Workflow, WorkflowStep, WorkflowTransition, WorkflowVersion

User = get_user_model()


def make_active_workflow():
    wf = Workflow.objects.create(name="W", slug="w-order")
    v = WorkflowVersion.objects.create(workflow=wf, version=1)
    s1 = WorkflowStep.objects.create(version=v, key="start", name="Start", order=1, is_start=True)
    wash = WorkflowStep.objects.create(version=v, key="washing", name="Washing", order=2, required=True)
    end = WorkflowStep.objects.create(version=v, key="end", name="End", order=3, is_terminal=True)
    WorkflowTransition.objects.create(version=v, from_step=s1, to_step=wash)
    WorkflowTransition.objects.create(version=v, from_step=wash, to_step=end)
    WorkflowEngine().publish(wf, v)
    PricingRule.objects.create(step=wash, name="Wash", rule_type="per_kg", amount=Decimal("5000"))
    return wf, v


class OrderServiceTests(TestCase):
    def setUp(self):
        self.user = User.objects.create_user(username="c", password="***")
        self.customer = Customer.objects.create(user=self.user)
        self.facility = Facility.objects.create(name="F")
        self.slot = Slot.objects.create(
            facility=self.facility, date=timezone.localdate(), start_time="08:00", end_time="08:30", capacity=5
        )
        self.reservation = Reservation.objects.create(customer=self.customer, slot=self.slot, status="confirmed")
        make_active_workflow()
        self.service = OrderService()

    def test_full_lifecycle(self):
        order = self.service.create_from_reservation(self.reservation)
        order = self.service.record_weighing(order, "1000", "80")
        self.assertEqual(order.net_weight_kg, Decimal("920"))
        order = self.service.select_steps(order, ["washing"])
        self.assertEqual(order.status, "awaiting_confirmation")
        self.assertEqual(order.price_snapshot["total"], "4600000.00")
        order = self.service.confirm(order)
        self.assertEqual(order.status, "confirmed")
        self.assertIsNotNone(order.confirmed_at)

    def test_required_step_missing(self):
        order = self.service.create_from_reservation(self.reservation)
        order = self.service.record_weighing(order, "1000", "0")
        with self.assertRaises(ApiError) as ctx:
            self.service.select_steps(order, ["end"])
        self.assertEqual(ctx.exception.code, "REQUIRED_STEP_MISSING")

    def test_weighing_immutable(self):
        order = self.service.create_from_reservation(self.reservation)
        order = self.service.record_weighing(order, "1000", "80")
        with self.assertRaises(ApiError) as ctx:
            self.service.record_weighing(order, "900", "0")
        self.assertEqual(ctx.exception.code, "WEIGHING_IMMUTABLE")

    def test_duplicate_order_for_reservation(self):
        self.service.create_from_reservation(self.reservation)
        with self.assertRaises(ApiError) as ctx:
            self.service.create_from_reservation(self.reservation)
        self.assertEqual(ctx.exception.code, "ORDER_EXISTS")